Numerous devices have been used to position tissue at a surgical site to aid in the performing of surgical procedures. Various retractors or similar devices, have been used for many years to hold an artery in position during operations adjacent to the heart to prevent movement of the artery. This serves to minimize the risk of injury to the artery and adjacent tissue and can facilitate the creation of the desired anastomosis.
A recently developed procedure, referred to as the minimally invasive direct coronary artery bypass procedure, has been used to graft onto a coronary artery without cardiopulmonary bypass. This procedure involves the grafting of the left internal mammary artery (LIMA) or saphenous vein onto the left anterior descending (LAD) or other coronary artery. As this procedure does not require the use of a heart lung machine to oxygenate and pump blood, the morbidity and mortality associated with this procedure is substantially lower than previous bypass techniques. A problem associated with the less invasive procedures, however, is that while the heart continues to pump during the procedure, the motion of the heart can interfere with the surgeon""s task of attaching the LIMA or saphenous vein to the LAD. There is also a need to stop blood flow in the area of the graft to maintain a clear field of view and provide precise suture placement.
Two basic strategies have been employed to address the problem of operating on a moving site, one being the use of pharmacological agents to limit heart motion, and the other being mechanical, such as a two prong retractor that is pushed down against the heart on both sides of the artery, or alternatively, upward traction away from the moving heart by suction, traction tape or suture thread. Both of these options, however, have problems associated with them. Both options are susceptible to some movement of the vessel graft site. The use of pharmacological agents is undesirable and may impair circulatory function. Traction by compression of the heart requires an increased amount of downward force on the tissue of the heart along a relatively large surface area. Although this type of device does serve to immobilize the tissue at the surgical site, it may also compromise the ability of the heart to maintain circulation and result in hypotension. Upward traction through the use of suction requires that the entire surface of the device be in contact with the tissue of the heart along a relatively large surface area to maintain suction. As with the compression type of devices, the suction type of device may cause injury, stenosis or occlusion of the vessel when upward traction that is sufficient to immobilize the tissue along the surgical site is used. Additionally, because various surfaces of the heart need to be accessed, it is not always possible or convenient to apply compression or upward traction to each surface of the heart.
There is a continuing need for improvement in devices and methods for retaining tissue at surgical sites to further reduce the risks associated with surgical procedures where the devices and methods are inexpensive, versatile, safe and reliable. The increased use of the above-described mechanical devices have also illustrated the need for a device that provides the desired local stabilization while allowing the surgeon to quickly set up and remove the stabilizing device while also providing access to multiple locations and surfaces on the heart of the patient.
The present invention relates to a cardiac stabilizer for immobilizing tissue at a surgical site and to a method of using the stabilizer during a surgical procedure. A preferred embodiment of the stabilizer includes a generally ovoid or elongate retaining element or platform having an aperture area that exposes the surgical site and a holder that is used to position tissue at the surgical site relative to the retaining element. A handle can be attached to or fabricated with the platform so that the user can manipulate the position of the stabilizer as needed. As used herein, the stabilizer generally refers to a device that is movable into a contacting relationship with the tissue of a patient to reduce the movement of the tissue at the desired surgical site.
The coronary arteries are typically about 1-2 mm in diameter, and the pumping heart can move these arteries over distances of several millimeters during each heartbeat. Because the movement of even 1 or 2 millimeters can result in a displacement of the grafting site that can substantially interfere with suturing an effective anastomosis, it is desirable to restrain movement of the artery at the surgical site in any direction to less than about 1 mm. The stabilizer and tapes of the present invention preferably restrain movement of the tissue relative to the stabilizer.
A preferred embodiment of the invention comprises a retaining element or stabilizer that includes a removable end piece that is removable to form an aperture area that is open to permit removal of the stabilizer from around the grafted artery following the procedure. The end piece is used to contribute to the stability of the stabilizer during the procedure and then is readily removable to allow for the passage of the grafted vessel therethrough. The stabilizer can be beneficial in any procedure where it is desirable to stabilize tissue at a surgical site. For example, the stabilizer can also be used for grafting vessels onto the diagonal, right or other coronary arteries without altering the heart""s pumping function or during surgery on various other organs or tissues.
In a preferred embodiment of the invention, a handle or articulating arm may be secured to the platform of the stabilizer and may be held in position by the user, attached to various locations on a retractor frame that is fixed around the operative site or simply clipped to a drape around the site.
In yet another preferred embodiment of the present invention, the stabilizer includes a generally ovoid or elongate shape wherein the lengthwise dimension of the stabilizer is greater than the width dimension. In this form of the invention, the connector for attachment to a handle or other member is located on the stabilizer generally along the an end portion of the stabilizer such that the application of force along the handle is applied over the blood vessel that is to be operated on and near the aperture area.
In a further preferred embodiment, the stabilizer has tape holder elements disposed in the longitudinal dimension and/or along the periphery of the stabilizer. Each holder element includes one or more slots that frictionally grip an end of a connector such as elastic tape or thread which extends through the tissue of the patient to connect the tissue to the stabilizer. The use of slots or grooves on the surface of the stabilizer allows the user to place the connectors such as elastic tape or thread around the outer surface of the stabilizer to position tissue at the surgical site within the stabilizer aperture and to minimize movement of the tissue relative to the stabilizer during the procedure. When these slots are used, the tapes are threaded through the tissue of the heart-wall of the patient and then aligned and drawn towards each other to be positioned in recessed areas along the periphery of the stabilizer. When the tapes are located in the recessed areas, the tapes are then drawn away from each other to be positioned in the desired retaining slots on the holding members. The surgeon can include additional tissue around the blood vessel as the tapes are tightened so that the blood vessel is compressed by the adjacent tissue rather than being directly constricted by the tapes. Additionally, the surgeon can position the tapes at a relatively wide angle of approach when the tapes are threaded around the outer surface of the stabilizer so that more tissue is positioned between the tapes and the blood vessel. The route used by the surgeon varies depending on the depth of the desired blood vessel and the surgeon""s preferred approach to performing the anastomosis. The combination of the stabilizer and the tapes provides a system that does not require the significant compression or upward traction as required by the prior devices to obtain a suitable surgical site.
In a further preferred embodiment, the stabilizer may also include a plurality of tabs extending downwardly from the bottom surface of the stabilizer along the ends of the aperture area. The use of the tabs in combination with the tapes causes the tissue in the aperture area to be raised upwardly a small amount to expose the portion of the blood vessel that is to be the subject of the anastomosis. Additionally, the tabs preferably extend downwardly from the ends of the aperture area to create contact surfaces along the ends sides of desired surgical site to further restrict the flow of blood through the blood vessel during the procedure.
When the present invention is used in a coronary artery bypass procedure, the stabilizer is positioned in a desired position along the myocardial surface of the patient. One or more tapes, for example, silastic tape (i.e. a silicon elastomer) or suture thread, are passed through the myocardium at a location adjacent to the artery grafting site with a blunt needle. The stabilizer is then loosely positioned in the desired relative position along the myocardium of the patient. Both ends of each tape are connected to the stabilizer platform with sufficient tension to draw the tissue into contact with the bottom surface of the platform and to occlude blood flow on the upstream side of the operative site. The stabilizer is then securely positioned in the desired relative position along the myocardium of the patient. The tape compresses the artery against the bottom surface of the platform and preferably against the tabs while the artery graft site is held in a fixed position relative to the aperture area. The coronary artery is opened longitudinally and the end of the mammary artery or other blood vessel is sewn to the graft opening with multiple fine sutures. Once the graft is completed, the end portion of the stabilizer may be removed to open the aperture area. The tape may then be released to restore blood flow to the blood vessel and the anastomosis is then inspected for hemostasis and other defects. The anastomosis is then readily removable from the end of the stabilizer through the open end of the aperture area.